1. Field of the Invention
The present invention relates to a coupling sleeve for a bus bar connection as defined in the preambles of the Patent Claims, as well as to a gas-insulated switchboard system as set out in the preambles of the corresponding secondary claims, which incorporates such a connecting sleeve.
2. Description of the Related Art
In switchboard systems with gas-insulated switchboard sections or with other modules that are connected to one another through bus bar connections, exacting demands are imposed not only on the electrical contacts, but also on the gas seals themselves.
Within the area of the bus bar connection, it is customary to use a connecting sleeve that is of an elastic material, often an elastomer, which is in the form of a tube so as to enclose the bus bar in a reliable fashion and insulate it against the environment.
EP-A-1 111 748 describes a bus bar connection that is fitted with such an insulating connecting sleeve (manchon isolant).
However, the insulating properties can be degraded by partial discharges and can deteriorate during the operating time of the switchboard system. So-called partial-discharge measurements (TE measurements) must be made in order to ensure safe operation and before the system is put into operation so as to identify possible damage to the insulating material and so as to ensure installation that conforms to the relevant standards. In addition to methods that are base on optical and ultrasound principles, a usual method is electrical TE diagnosis (according to IEC 60270), in which the occurrence of partial discharges is monitored and recorded over time by using measuring sensors, which are also referred to a coupling electrodes, when the measurement signals obtained are subjected to intensive signal analysis. The signal analyses are completed in different frequency ranges that extend into the GHz ranges, which is to say into the UHF (ultra-high frequency) ranges. If signal analysis is completed in these ultra-high ranges, this is also referred to as UHF-TE diagnosis.
A UHF sensor (UHF coupling electrode) is usually integrated into a cast-resin part that is positioned in the gas chamber of the system in order to record the measurement signals. Or it is provided with a voltage take-off, by way of the bus bar.
These known measures entail the disadvantage that additional components with a not inconsiderable space requirement have to be built in, and this results in additional costs. In addition, in order to wire up the sensors and voltage take-offs, additional seals are needed to route the wiring out of the system. Furthermore, it is only possible to replace the sensors by entering the system gas chamber, and this makes additional gas work necessary.
For this reason, it is the objective of the present invention to propose a solution to these problems which permits reliable UFH TE diagnosis that is both safe and as simple as possible to be performed on a bus bar connection for gas-insulated switchboard systems.